Embodiments of the present disclosure generally relate to semiconductor packages and methods of fabricating the same and, more particularly, to bump structures in semiconductor packages and methods of fabricating the same.
Electronic devices employed in electronic systems may include various circuit elements such as active elements and/or passive elements. The circuit elements may be integrated in and/or on a semiconductor substrate, thereby constituting an electronic device (also, referred to as a semiconductor chip or a semiconductor die). The electronic device may be mounted on a printed circuit board (PCB) or a package substrate to produce an electronic device package, for example, a semiconductor package. The package substrate may include circuit interconnections such as silicon interposers. The electronic device package may be mounted on a main board to constitute an electronic system, for example, computers, mobile systems, or data storage media.
Bumps are widely used in fabrication of the electronic device packages. The bumps may electrically connect the semiconductor chip in the electronic device package to the package substrate or may electrically connect the semiconductor chips in a single electronic device package to each other. For example, the bumps may be employed in flip chip packages to realize various stack structures of the semiconductor chips and/or to increase the number of input/output (I/O) terminals of the flip chip packages.
As the semiconductor chips become more highly integrated and become scaled down, the sizes and pitches of the bumps have been continuously reduced. In fabrication of the bumps, a metal material may be introduced into the bumps to electrically connect the semiconductor chips to each other. For example, the fabrication of the bumps may include depositing a seed metal layer which is used to grow the metal material. The seed metal layer may be removed using a wet etch process in a subsequent process. In such a case, the seed metal layer may be over-etched by increasing the wet etch time in order to completely remove the seed metal layer. However, if the seed metal layer is over-etched, undercut regions may be formed under the bumps, which may laterally grow in size thereby causing failures. If the seed metal layer is over-etched, contact areas between the bumps and the underlying layer may be reduced to increase contact resistance of the bumps.